NEETZoologyPrinciples of Inheritance and Variation
A couple has four children, and interestingly, each child has a completely different blood group: A, B, AB, and O. Which of the following represents the correct genotypes of the parents?
Options
- AI^ A I^ A and I^ B I^ B
- BI^ A I^ B and ii
- CI^ A i and ii
- DI^ A i and I^ B i
Correct answer
D. I^ A i and I^ B i
Step-by-step solution
For a child to have blood group O, their genotype must be ii , which means they must inherit one i allele from each parent. Therefore, both parents must carry at least one recessive i allele. For a child to have blood group AB, their genotype must be I^ A I^ B , which means one parent must provide the I^ A allele and the other must provide the I^ B allele. Combining these deductions, one parent must have the genotype I^ A i and the other must have the genotype I^ B i . A cross between I^ A i and I^ B i yields offsp